It is often required to produce optical devices having accurately aligned optical fibers. When light is transmitted from one fiber to another a number of conditions can cause large light losses. Poor alignment is a major source of inefficiency. If a pair of fibers are laterally displaced by 10% of the fiber core diameter a 0.5 dB optical power loss will result. Thus, for a fiber having a diameter of 100 micrometers, a misalignment of 10 micrometers will cause a loss of 10% of input power. Similarly, an angular misalignment will also cause significant losses.
It is also required to produce optical sensors which are very compact, requiring curved fiber paths within a small package which also contains a gap between aligned fiber ends to eeceive a toothed wheel or other modulating device. Fabricating such sensors on a mass production basis provides a challenge which is not met by prior art methods.
Several schemes have been proposed for fiber connectors, splices, etc. which allow efficient end-to-end coupling of straight fibers. Some such devices use alignment aids such as V-grooves in support plates to hold straight lengths of fibers in registry. Other devices use a common surface such as a continuous tube to hold both fibers. In general, these techniques are useful when straight fibers are being spliced and the support for the fibers is continuous, but do not apply in sensors where the fibers must be curved or when a substantial gap between the fiber ends is needed.